As a chemical/physical phenomenon detecting device, a pH sensor disclosed in Patent Document 1 is known.
In a conventional chemical/physical phenomenon detection device, charges existing in a sensing region are transferred to a charge accumulation region and accumulated therein, the charges thus accumulated are measured to identify chemical phenomenon or physical phenomenon to be detected.
By surrounding the sensing region with a weir of a predetermined potential, a potential difference between the potential of the weir (e.g. TG region) and the potential of the sensing region is proportional to the amount of charges that can be present in the sensing region. Since the potential of the sensing region changes according to the change in the chemical phenomenon or the physical phenomenon (external environment) to be detected, the change in the external environment is reflected in the potential difference between the potential of the sensing region and the potential of the weir. The sensing region can hold an amount of charges corresponding to the environment exists. Charges in the sensing region are transferred to the charge accumulation region by changing the potential of the TG region that is a part of the weir.